The present invention relates to skateboard trucks and the mounting of skateboard wheels thereon.
In the past skateboards have been constructed with a pair of trucks located along the center line and on the underside of a longitudinally elongated platform, the upper surface of which is termed a deck. One truck is located near the forward end of the platform while the other truck is located remotely therefrom near the rear end of the platform. Each of the trucks carries a pair of skateboard wheels on axle segments extending laterally outward from either side of the platform center line in opposing directions in fixed disposition relative to each other. Each axle segment carries a single wheel, so that the skateboard is supported upon four wheels.
In conventional skateboards, the forward truck is attached to the underside of the skateboard platform by screws or other fasteners. The forward truck includes a downwardly extending post which entraps a yoke or other mounting structure between a pair of compressible resilient bearings. Frequently the yoke includes a longitudinally extending pivot pin, inclined upwardly and forwardly toward the underside of the platform and along the center line thereof. The forward extremity of this pivot pin is typically rotatably seated in a socket also mounted upon the truck. A single axle or opposing axle segments extend laterally outward from either side of the yoke in fixed disposition thereto, and skateboard wheels are rotatably mounted thereon. A similar truck, with a pivot pin mounted in a direction 180.degree. opposite the pivot pin of the front truck, is provided at the rear end of the skateboard with a rearwardly extending pivot pin.
The skateboard rider is able to propel himself along a reasonably smooth roadway or other rolling surface and to maneuver or steer the skateboard by shifting his weight laterally from side to side, and to perform stunts on the board by both longitudinally and laterally shifting his weight.
It is to be understood that the term roadway, as used in the description herein, is intended to refer broadly to any surface upon which a skateboard can be operated. Thus, this term is intended to include such surfaces as sidewalks, streets, drained swimming pools, the insides of concrete pipe, and numerous other surfaces upon which skateboards may be operated.
When the skateboard rider laterally shifts his weight on the skateboard the platform is tilted relative to the laterally extending axles or axle segments. Such tilting is possible because resilient bearings about the post of the truck are compressed to a considerable degree on one side of the skateboard, while pressure is relieved from these bearings on the opposite side. This results in an increased downward pressure on the skateboard wheels on the side of the board bearing the greatest weight. Consequently, the wheels on this side are resiliently flattened to a slight degree, thus creating a small drag on the forward rotation of the wheels on that side. At the same time, since presssure is relieved from the opposite side of the board, and because of the downward pressure on the side of the board to which weight is shifted, the axle orientation shifts from a horizontal disposition to an attitude in which the axle is inclined downwardly toward the roadway surface upon which the skateboard is propelled on the side of the skateboard to which the increased weight is applied and lifted at the opposite side. This tends to lift the wheels of the skateboard from the roadway surface on the side opposite that to which increased weight is shifted. When the skateboard is manipulated in this manner, the socket of the truck receiving the pivot pin tends to rotate relative to the pivot pin in the direction toward which weight is shifted. Movement of weight relative to the platform effectuates a departure of movement of the skateboard from a straight line, and instead causes the skateboard to move in an arc about a point displaced laterally from the skateboard in the same direction toward which weight on the skateboard is shifted.
Certain deficiencies exist in the operation of conventional skateboards. For example, because the wheels of each truck are locked in coaxial alignment, tilting of the platform down on one side, while attempting to turn, tends to slightly raise the skateboard wheels off of the rolling surface at the opposite side. As a result, contact of the skateboard with the rolling surface is more concentrated at the wheels remaining in firm contact with the road surface. This decrease in the breadth of contact with the rolling surface results in a deterioration of control over the movement of the skateboard. Moreover, in this condition the skateboard is much more likely to slide laterally out of control should it strike a road hazard, such as a pebble or spot of oil, or especially when extreme turning radii are attempted to avoid roadway hazards such as minor chuckholes and other depressions or obstructions.